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Although commercial string sets are available for all standard plucked instruments, sometimes a musician wants a custom set of strings for a specific tuning or an unusual scale length or an oddball instrument. Commercial string sets for extended range and multiscale instruments are not always available. Figuring out an appropriate string set has historically been a matter of trial and error. In recent years the availability of online string tension calculators has helped, but the process of assembling a string set using a tension calculator is still slow and tedious and has to be done one string at a time.

Here is a free (for non-commercial use) and easy-to-use calculator that will calculate a complete string set for you. It works for any acoustic or electric plucked instrument that can be strung with guitar strings, from baritone guitars to piccolo mandolins. All you have to do is enter the type of strings (electric, nylon, acoustic steel string), the scale length (for multiscale instruments, two scale lengths), and the note for each string, and the calculator will perform all the calculations and email you the specifications for your string set, composed of D'Addario single guitar strings. Not only that, it will also include specs for an additional higher tension string set and an additional lower tension string set. And if one or more of the strings in the set could be either a plain or a wound string, the calculator will provide specs for both, so you can choose which one you want.

Terms of Service

The calculator is free to use for non-commercial use only. It may not be used for AI training or content. If you want to use it commercially please see the section on this page about commercial licensing. As for all calculators on this site, this one is offered for use "as is" without any express or implied warranty. Calculator results tables are delivered to you via email as a PDF file. Email addresses are not retained long term and are never used for any other purpose. The calculator results tables are copyrighted text and may not be published (on websites, discussion forums, social media, etc.) without permission.

The Calculator

Use of the calculator is straight forward and self-explanatory. Answer the questions in the form and the calculator will inform you if it can spec out string sets based on the information you provided. Particular care should be taken when specifying the note for each string in the set. This is done by specifying both a note name and an octave number, using the format called Scientific Pitch Notation. See this Table of Musical Notes, which contains the notes of some strings of some common instruments that can serve as references. If it can spec out a string set, the calculator will then prompt you for some more information, including the email address to ship the string set(s) specification to, and then it will email you the results.

The calculator builds string sets from some commonly available D'Addario single strings. I have no affiliation with D'Addario. More detailed information about the parameters, the status messages, and the returned results appears on this page following the calculator.

Detailed Information

Although the calculator's parameters, status information, and its output tables are generally self-explanatory, a little more information about these can be helpful.

Parameter information

Type of strings - The calculator offers three types of strings, corresponding to the single strings that D'Addario makes available for electric guitars, steel string acoustic guitars, and nylon strung guitars. Electric guitar strings are required for instruments that have magnetic pickups. They consist of a range of diameters of plain steel strings and a range of nickel plated steel wound steel strings. Steel string acoustic guitar strings can be used for acoustic instruments ranging in pitch and size from the mandolin family up to the acoustic baritone guitar. They consist of a range of diameters of plain steel strings and a range of phosphor bronze wound steel strings. Nylon strings are used for acoustic instruments ranging in pitch and size from the soprano ukulele up to the nylon strung acoustic baritone guitar. They consist of a range of diameters of plain clear nylon strings and a range of silver plated copper wound strings with nylon floss cores.

Number of Strings - The total number of strings in the string set. Any value from 1 to 16 can be entered here.

Multiscale instrument? - If the string set is to be designed for a multiscale (also called multiple scale length or fan fret) instrument then select "Yes" here, and you'll need to enter both the treble side and bass side scale lengths in a later parameter.

Scale length units - You can select whether you want to specify the scale length(s) in inches or millimeters. Note that in the string set specifications generated by the calculator, dimensions are output in both inches and millimeters.

Scale length(s) - The scale length(s) for the instrument are specified here. The calculator can accommodate scale lengths from 10" (254mm) to 30" (762mm). The maximum length is limited by the lengths of guitar strings, typically about 41" (1041mm). It is a good idea if a scale length at or near 30" (762mm) is specified to be sure that a guitar string will be long enough for use on this instrument. If this is a multiscale instrument then scale lengths must be set for both the treble and the bass sides.

String notes and octaves - The note name and octave number for each string, in Scientific Pitch Notation. This is the place where most parameter errors occur, particularly with the octave numbers. If you are not completely comfortable with specifying pitches this way, it is a very good idea to make use of the Table of Musical Notes, which contains the notes of some strings of some common instruments that can serve as pitch references. It may also help to select one of the presets for common instruments first. This way if your set is a variation of a conventional set you won't have to specify each note and octave in the set. The blue "play" buttons are also helpful to be sure you are selecting the needed pitches. Click on a button to hear that pitch. Note that the play buttons only work for the note range of the piano. The calculator will design the string set with the exact pitch information you give it.

Note that the order of notes in the string set is important for multiscale string sets! The calculator expects the highest pitched note in a multiscale string set to be string #1, and for subsequent string numbers to be successively lower in pitch. This order is essential for multiscale string sets. For single scale length sets it is not important at all, but the general convention is useful even so.

Oddball string sets and multiscale

By convention most string set specifications are arranged so the pitch gets lower as the string number gets higher. Sets arranged like this are easy to specify using the calculator, whether they are single scale or multiscale. But there are some conventional string sets that don't follow this pattern, and specifying multiscale versions of these requires some additional steps.

Reentrant tuning - Typical reentrant tuning has the pitch getting lower as the string number gets higher for most of the strings, but the bottom most string is tuned to a higher pitch than the string above it. Conventional tuning for ukes is like this. Although there is no reason you can't specify a multiscale reentrant string set, it really doesn't make any sense to do so, at least given the reasons most people want multiscale instruments in the first place.

Strings in courses of identical strings - This is the way mandolin family instruments are typically arranged. If you want to specify a multiscale string set of this type, the best way to do this is to specify the set as if it just has one string per course (so, like a four string mandolin) and then buy two such sets of strings for the instrument. Since the calculator does not have any way of knowing that strings may be grouped into courses, specifying a multiscale eight string mandolin set (for example) would have the calculator assign a different scale length for each string, as if all eight strings were equally spaced across the width of the fretboard, which is not really what you want.

Strings in courses containing octave strings - This is the way the bass strings of the 12 string guitar are typically arranged. Multiscale instruments of this configuration have the same issue with scale lengths as for the configuration above. The thing to do here is to specify the string set as two separate six string sets - one for the treble side strings of each course, and one for the bass side strings of each course.

Status information

After the OK button is clicked the calculator will determine if it can design a string set with the scale length(s) and pitches you specified. If it can it will tell you that, and it will also tell you if it was able to design a higher tension and lower tension set. If it can not design a string set, it will tell you the numbers of the strings that it could not calculate physical strings for.

The calculator performs a lot of calculations to determine the optimal string for each scale length and pitch. But when it can't calculate a string that is even acceptable, the two most common reasons are 1. The pitch is too high for a string at this scale length, or 2. The pitch is too low for a string at this scale length. If the calculator cannot select one or more acceptable high pitched strings, then the pitch(es) will have to be lowered or the scale length shortened. If the calculator cannot select one or more acceptable low pitched strings, then the pitch(es) will have to be raised or the scale length lengthened. You can make any changes to string pitches and scale lengths you like and then try again.

If a string set was successfully designed, the calculator will present you with a few more fields to fill in so it can email the string set specifications to you. It will ask you to enter a name for the string set, your name, and the email address to which the string set spec document should be sent. All of this information will appear on the spec document. It is important to get the email address right! The calculator may be able to warn you about a bad email address in some cases, but not in all cases. And of course you'll want to be sure to whitelist the LiutaioMottola.com domain (where the message will originate) and to be sure your email client can accept email with PDF attachments.

String set tables

The emailed PDF file contains the string set specifications tables, one set per page. The header part of each table contains information identifying the string set and where it came from. Below that, there is information on each string in the set, one string per line. The first column contains the string number. If the calculator specified both plain and wound alternates then that information will be included next to the string number. The second column indicates the pitch of the string. The third column specifies the scale length for the string. If the string set is multiscale then each string number will have its own scale length. The fourth column contains the part number and description of the string. Use this information to purchase the strings needed. Finally, the fifth column specifies the tension the string will be under when tuned to the specified pitch at the specified scale length.

A note about plain and wound alternate strings. There are no hard and fast rules about where in a string set the transition from plain to wound should be. A few common examples show this to be true. Steel string electric guitars usually use plain strings for the top three strings and wound strings for the bottom three. But acoustic steel string guitars most often use plain strings for only the top two strings. Classical guitars commonly use plain strings for the top three strings, but wound G strings are available and are often used to improve the similarity of timbre across the string set. If you are requesting a string set that is similar to a conventional set then a good place to start is to make the plain-to-wound transition at the same string as for that conventional set. If your string set is a more radical departure from the norm, it is wise to buy all of the alternates and try them out and see what configuration you like best.

What the Calculator Does

Here is a very short and non-technical explanation of what the calculator is doing to come up with each string set. The first thing it does is to calculate a target average tension, based on the string set type, scale length(s), and pitches you specify. Next, for each string it searches its string library to build a list of candidate strings that will be near that tension at the specified scale length and pitch. It rejects strings that would likely break when tensioned to the target average tension. It also rejects strings with tensions that will be outside the tension variability normally found in commercial string sets. And it also rejects strings that would exhibit high inharmonicity (a measure of how "pure" the vibrating string would sound). Finally, it selects the best string from those remaining, based primarily on tension and inharmonicity considerations.

Commercial Licensing

The String Set Calculator is available for free non-commercial use only. If you want to use it commercially in any way please contact me for reasonable licensing terms. Customizations of the calculator are also possible, including re-hosting, re-branding, and the use of exclusive alternate string libraries. If you are a string manufacturer or string retailer and would like your advertising to appear on this page or in the results pages generated by the calculator, please contact me.

Bugs and Feature Requests

Although I can't promise to fix every bug or consider every feature request, I do appreciate all feedback you want to provide. Please contact me and provide as much detailed information as you can.

Please note that the most frequent feature request is to add additional strings to the calculator's string library. I would love to do this, but doing so requires me to buy each of the strings, take measurements, and add them to the library. This is an expensive and time-consuming process. It is unlikely I will include additional strings unless someone is willing to subsidize that work, or if the manufacturer of the strings provides me with the data needed by the calculator.

Acknowledgments

The calculator is built using the following open source software libraries. Thanks to all the license holders for making your work product available.

• File System Access API, Thomas Steiner, Apache 2.0
• jQuery, Open JS Foundation, MIT
• MIDI.js, Mudcube, MIT
• Bootstrap, Bootstrap Team, MIT